Cotton harvester units include a number of spindles and doffers for harvesting cotton. Doffer columns have a plurality of doffers for removing picked cotton from the spindles. A doffer is a disc that may be coated in rubber or urethane and rotatably driven at a velocity much greater than that of the spindles. In a conventional cotton harvester row unit, the spindles move underneath the bottom face of the doffers so that the cotton is unwrapped and stripped from the spindles. In this conventional system, a doffer drive system is mechanically driven off a spindle drive system, or at the very least the two systems are mechanically coupled to one another. Mechanical coupling of the doffer and spindle drive systems enables the speed relationships to be maintained, and also achieves proper functionality when the systems operate in harvest mode. In other words, the spindles can operate in a desirable direction of travel.
There are, however, circumstances or applications in which independent control of the doffer may be desirable and which conventional systems are unable to achieve. In particular, it may be desirable to have independent control when a row unit plug is being cleared. When a row unit plugs, spindles often become wrapped with cotton which can jam or interfere with the desirable forward rotation of the picking unit components. Thus, a need exists to independently control the doffer drive system and spindle doffer system from one another so that when the spindles become plugged, the doffers can continuously be driven in the forward direction while the spindles are rotatably driven in a reverse direction. In doing so, the doffers could unwrap the cotton from the spindles without requiring any manual intervention.